Laser marking is capable of marking characters, symbols and patterns and the like. Laser marking is a marking method using high power density laser to irradiate a portion of work piece to gasify surface material or generate chemistry reaction of colour change, thusly leaving a permanent mark.
In the conventional marking machine, marking software may keep configured pixels according to resolution settings of an operator and perform a gray scale calculation according to the three sub-pixels of red, green and blue, thusly obtaining a gray scale value of each pixel. The gray scale difference of an image may be presented by a number of marking points per unit area, that is, the gray scale may be presented dependently on a density of marking points. Since the unit area is too small to be detected by naked eyes, only continuous change in pictures may be felt. In the conventional marking technology, the marking control is separate from the laser control. In the laser control, a segment control is employed, which is coarse, and not accurate enough to be used in the control of marking points, such that the marking resolution is not high enough and the marking efficiency is low.
Moreover, different materials have different capacities of absorbing laser. Thusly, it is needed to select different laser devices by human when processing laser marking on different materials. For example, when marking a mobile phone case, if the case is plastic or carbon fiber, a power within 5 w should be adopted, an over-large power may directly ruin the case; however, to a metal case, over 20 w power should be adopted, a too small power may lead to unsuccessful marking. When a user needs to perform marking on different materials, he or she has to buy marking machines with different output powers, which severely increase the expense burden of the user.
As a result, one of technical problems that a skilled person in the art needs to solve urgently is, how to match the output power of the laser marking machine with the material to be marked.